The Timber Rattlesanke is a pit viper which has highly sensitive
organs for locating prey, by heat-sensing. These pits are
easily seen in the photos of this Timber Rattlesnake found
in Southern Illinois.

Glands behind the eyes, produce and store the venom. From
the glands the venom passes through hollow fangs. The Timber
Rattlesnake does have voluntary control over each fang. It
can raise one, both or none when striking.

Pit vipers always have replacement fangs, as seen in the
photograph you can see two fangs on each side. When and if
bit there may be one, two, three, or even four puncture wounds.
A dry bite is when no envenomation occurs and basically the
snake missed.

Due to rattles breaking during the snake's life, one cannot
determine the snake's age by counting the number of rattles.